The present invention relates generally to the field of prime mover systems and, more particularly, to a redundant prime mover system.
Large shaft driven machines, such as compressors or pumps, are typically driven by a single prime mover, such as an electric motor or engine. For example, compressors on natural gas pipelines are typically driven by an engine or turbine that burns natural gas from the pipeline. In locations where electricity is readily available, the compressor may be driven by an electric motor.
Motor/generators have been added to engine or turbine driven compressors to generate startup torque and to generate electricity from the excess output power generated by the engine or turbine when the power requirement of the compressor is less than the output power generated by the engine or turbine. Such a system is designed to continuously operate the engine or turbine at an optimal level during all seasons no matter what the power requirement of the compressor is. As a result, this system is not designed to selectively run the compressor in more than two operating modes. Moreover, the system is not designed to generate and sell electricity back to the electric utility.
Another system uses a hydraulic turbine, motor/generator and pump combination wherein the motor/generator drives the pump to pump water into a reservoir in one mode and when the water is removed from the reservoir, the water drives the hydraulic turbine which drives the motor/generator to generate electricity. Similarly, a gas turbine, motor/generator and compressor combination has been used in a two operating mode system. The gas turbine drives the motor/generator to generate electricity when the compressor is not used, and the motor/generator drives the compressor when the gas turbine is not used. These systems are not designed to selectively run the compressor in more than two operating modes depending on various parameters.
Accordingly, there is a need for a redundant prime mover system that provides increased reliability, versatility and efficiency.
The present invention provides a redundant prime mover system that can be operated in three or four different operating modes, which increases the reliability, versatility and efficiency of the system. The present invention includes an engine or turbine, a motor/generator and a machine, such as a compressor or pump. The four different operating modes are: driving the machine with the engine or turbine; driving the machine with the motor/generator; driving the machine and the motor/generator with the engine or turbine such that the motor/generator generates electricity; and driving the machine with both the engine or turbine and the motor/generator in a load sharing arrangement. The system can be selectively switched between these modes depending on one or more parameters. As a result, the present invention can be set to run in the most cost effective mode or can arbitrage the price differences between electricity and the fuel used by the engine.
The present invention provides a redundant prime mover system to drive a machine having an engine coupled to the machine, a motor/generator coupled to the machine and an electrical network connection, and a controller communicably coupled to the engine and the motor/generator. The controller has at least three operating modes. The first operating mode drives the machine with the engine. The second operating mode drives the machine with the motor/generator. The third operating mode drives the machine and the motor/generator with the engine such that the motor/generator generates electricity for delivery to the electrical network connection. Alternatively, the third operating mode drives the machine with both the engine and the motor/generator. This alternate operating mode can also be included as a fourth operating mode.
In addition, the present invention provides a redundant prime mover system to drive a machine having a motor/generator coupled to the machine and an electrical network connection, an engine coupled to the motor/generator, and a controller communicably coupled to the engine and the motor/generator. The controller has at least three operating modes. The first operating mode drives the machine with the engine. The second operating mode drives the machine with the motor/generator. The third operating mode drives the machine and the motor/generator with the engine such that the motor/generator generates electricity for delivery to the electrical network connection. Alternatively, the third operating mode drives the machine with both the engine and the motor/generator. This alternate operating mode can also be included as a fourth operating mode.